Ultrafast dynamics and efficient manipulation of antiferromagnetic skyrmioniums by voltage-controlled magnetic anisotropy gradient

Current-induced spin torque is widely regarded as a popular and effective method for driving magnetic textures in spintronics. However, attaining fast dynamics requires a large current density, which inevitably results in significant Joule heating. Here, the voltage-controlled magnetic anisotropy gradient, an alternative scheme that accommodates ultrafast dynamics and low-Joule heating, is proposed to excite the magnetization dynamics. We analytically and numerically study the dynamics of an antiferromagnetic skyrmionium driven by the magnetic anisotropy gradients. The numerical simulations demonstrate that antiferromagnetic skyrmioniums can be effectively driven by voltage-controlled magnetic anisotropy gradients, with one order speed-up compared to their ferromagnetic counterparts. In addition, the isotropic deformations of antiferromagnetic skyrmioniums are also identified and investigated, which are distinct from their ferromagnetic counterparts. Furthermore, a structure is designed to achieve the transition from antiferromagnetic skyrmionium to skyrmion. Our results deepen the understanding of antiferromagnetic skyrmionium dynamics and provide ideas for building future antiferromagnetic skyrmionium-based spintronic devices.